1. Field of the Invention
The invention relates to a pattern processing method regarding a character font memory to store character font data by a form of a coordinate point array, a character pattern generating apparatus using such a character font memory for generating a character pattern on the basis of the font data, or the like.
2. Related Background Art
As typical apparatuses using such a kind of character pattern generator, there are a printer, a display apparatus, and the like provided with character font data called vector fonts, outline fonts, or scalable fonts which can generate characters with various modifications or characters of many kinds of sizes.
In the above apparatuses, an outline of reference character data is provided as absolute coordinates of each of the coordinate points constructing such an outline, those coordinate values are multiplied on the basis of a magnification ratio or a reduction ratio according to a designated output size, the coordinate values of the outline corresponding to the designated character output size are calculated, and a character pattern is derived. Therefore, a variation occurs in thicknesses of line segments of a character which should inherently be uniform as shown in FIG. 4B due to a quantization error or the like which occurs when a character pattern is reflected to lattice points of a dot pattern at the designated character size to be finally generated. Particularly, in the case where a character pattern has been converted into a character of a small size, there is a problem such that a deterioration in apparent quality is remarkable.
FIG. 4A is a diagram showing outline character pattern data of a type style Helvetica of European language fonts. FIG. 4B is a diagram showing an example of a dot pattern when characters have been developed into dot patterns by a conventional technique. As will be obviously understood from FIG. 4B, a vertical line portion shown by reference numeral 41 of a character "H" and lateral line portions shown by reference numerals 42 and 43 of a character "E" are reproduced thinner than the other portions due to a quantization error when converting character patterns into dot patterns.
To solve the above problem, therefore, there is considered a method whereby an arbitrary coordinate point on an outline constructing reference character data is used as a reference, the coordinates of the reference point are stored as absolute coordinate values, other arbitrary coordinate points on the outline are made related by relative distances from the reference point, thereby preventing the deterioration in character quality mentioned above. FIG. 4C shows an example of character patterns which are generated as mentioned above. That is, by controlling thicknesses of vertical and horizontal lines constructing the character patterns, the thicknesses of the line segments shown at 41 to 43 in FIG. 4B are equalized with those of the other line segments, so that a character pattern of a higher quality can be generated.
In the above conventional example, however, only the thicknesses of the line segments constructing a character pattern can be controlled. To reproduce a design of a complicated stroke shape as represented by a type style such as Optima of European language fonts shown in, for example, FIG. 5A, asymmetrical unbalanced character patterns are obtained as shown in FIG. 5B and character patterns of a high quality cannot be displayed and generated.